Historically, ‘civilisation’ = people moving from rural areas to city. ‘collapse of civilisation’ = people abandoning cities and moving back to rural areas. That is all.
In this case the overwhelming majority of people are very dependent on centralized setups for production, safety and other things. And rural areas prolly lack capacity for most of them
Maybe I am overthinking this, but it seems to me like either the elites get the totalitarian control they want, or there will be lots and lots of armed conflicts all over the place.